NASA SLS/Orion/Payloads

[tater]

1 minute ago, Bill Phil said:

Well, at least ICPS will see some actual use...

Centaur would be better, lol. I'm unsure why ICPS and EUS (another DCSS variant) were picked. I assume it was to throw a bone to Boeing, even though Centaur (or a new variant) would have been unambiguously superior.

[Bill Phil]

1 minute ago, tater said:

Centaur would be better, lol. I'm unsure why ICPS and EUS (another DCSS variant) were picked. I assume it was to throw a bone to Boeing, even though Centaur (or a new variant) would have been unambiguously superior.

Centaur isn't as large, it would need to be stretched or widened for Orion. Probably better for lighter payloads though.

[tater]

Just now, Bill Phil said:

Centaur isn't as large, it would need to be stretched or widened for Orion. Probably better for lighter payloads though.

That's why I said a variant. ACES is such a variant, and as a new stage---just like EUS, which also doen't exist until built.

Centaur writ large is still better.

[Bill Phil]

6 minutes ago, tater said:

That's why I said a variant. ACES is such a variant, and as a new stage---just like EUS, which also doen't exist until built.

Centaur writ large is still better.

A variant might, but it's too late now. 

ICPS is based on the larger DCSS variant, and is better for larger payloads than Centaur, atm. A two engine Centaur might be good for heavier payloads to LEO.

[tater]

34 minutes ago, Bill Phil said:

A variant might, but it's too late now. 

ICPS is based on the larger DCSS variant, and is better for larger payloads than Centaur, atm. A two engine Centaur might be good for heavier payloads to LEO.

I should be clear that I'm talking mostly about EUS, which also doesn't exist, not ICPS. Of course ICPS was only supposed to be used once, so it didn't matter. If they had planned to fly the first block many times, then they should have picked an upper stage that didn't suck.

[sevenperforce]

32 minutes ago, tater said:

I should be clear that I'm talking mostly about EUS, which also doesn't exist, not ICPS. Of course ICPS was only supposed to be used once, so it didn't matter. If they had planned to fly the first block many times, then they should have picked an upper stage that didn't suck.

Indeed. ICPS sucks so hard that Block 1's theoretical LEO payload with ICPS is roughly the same as it would be if you took off ICPS entirely and just sent the core all the way to orbit, DIRECT/Jupiter style.

Edited April 23, 2018 by sevenperforce

[Canopus]

21 minutes ago, sevenperforce said:

Indeed. ICPS sucks so hard that Block 1's theoretical LEO payload with ICPS is roughly the same as it would be if you took off ICPS entirely and just sent the core all the way to orbit, DIRECT/Jupiter style.

I'm pretty sure the LEO capacity always given is already only the center core without upper stage. And the thing Is that nobody ever had the idea to use SLS to send anything into LEO. 

They chose the 5 meter DCSS because it was a stage that already existed at the time (unlike the 5 meter Centaur V which wasn't even on the drawing board). I don't think any other stage would have made much more sense.

Edited April 23, 2018 by Canopus

[sevenperforce]

6 minutes ago, Canopus said:

I'm pretty sure the LEO they give is already only the center core without upper stage. And the thing Is that nobody ever had the idea to use SLS to send anything into LEO. 

If you put a 70-tonne payload on top of ICPS, you could just barely get it into LEO. If you put the same payload in place of ICPS, you could just barely get it into LEO.

It is a sucky, sucky stage which doesn't actually improve the throw of a launch vehicle to a given orbit (even though ICPS's BLEO performance is obviously better than that of a bare core).

[Canopus]

1 minute ago, sevenperforce said:

(even though ICPS's BLEO performance is obviously better than that of a bare core).

Which is the whole point. 

Edited April 23, 2018 by Canopus

[sevenperforce]

5 minutes ago, Canopus said:

Which is the whole point. 

Not disputing.

[Canopus]

24 minutes ago, sevenperforce said:

It is a sucky, sucky stage which doesn't actually improve the throw of a launch vehicle to a given orbit.

Isn't this a bit undue? The big DCSS must be the highest performing upper stage there is right now.

Edited April 23, 2018 by Canopus

[Bill Phil]

39 minutes ago, sevenperforce said:

Indeed. ICPS sucks so hard that Block 1's theoretical LEO payload with ICPS is roughly the same as it would be if you took off ICPS entirely and just sent the core all the way to orbit, DIRECT/Jupiter style.

That's because SLS Block 1 isn't a LEO vehicle. ICPS is part of the 70 tonnes to LEO and is intended to send payloads BLEO. 

The biggest problem is the core. It's underpowered. It has ridiculous gravity losses. This hurts performance quite a bit. Not to mention performance varies depending on which engines they choose.

[sevenperforce]

11 minutes ago, Canopus said:

Isn't this a bit undue? The big DCSS must be the highest performing upper stage there is right now.

DCSS is a great stage for the Delta IV but it does not have enough thrust to be terribly useful on top of the SLS.

[Canopus]

3 minutes ago, sevenperforce said:

DCSS is a great stage for the Delta IV but it does not have enough thrust to be terribly useful on top of the SLS.

Why would it need much thrust. It's pretty much already in orbit when it is started. I know you're going to lose some delta v to gravity loss but it can't be that bad.

[sevenperforce]

1 hour ago, Canopus said:

Why would it need much thrust. It's pretty much already in orbit when it is started. I know you're going to lose some delta v to gravity loss but it can't be that bad.

Needs more thrust if it is to be used for any sort of variable mission profile.

[Bill Phil]

25 minutes ago, sevenperforce said:

Needs more thrust if it is to be used for any sort of variable mission profile.

Well it was never intended to be used much.

[Canopus]

47 minutes ago, sevenperforce said:

Needs more thrust if it is to be used for any sort of variable mission profile.

What sort of mission profile are you thinking of? 

[tater]

1 minute ago, Canopus said:

What sort of mission profile are you thinking of? 

Anything actually variable? Right now SLS can do basically nothing useful as I see it. It can send a capsule into a distant lunar orbit, or it can send a space probe someplace. Other vehicles can also do the same. If a LV is going to literally cost a few billion $ every time it flies, and it is desperate for payloads to justify its existence (vs busywork that merely uses its existence), then it should have as broad a range of applications as possible. That is simply not true right now.

We can change the requirement we use from "mass to LEO" to, "mass to LLO," or mass to TLI, if that gives it a fairer comparison, I suppose.

Here's a question back regarding missions:

What missions do you suggest to be launched once per year to justify the existence of the SLS program? (forgetting that it's just a jobs program that happens to make a rocket)

[_Augustus_]

http://www.foxnews.com/opinion/2018/04/22/newt-gingrich-glimpse-america-s-future-in-space-in-2024.html

Newt Gingrich: Kill SLS already, otherwise the US looks like a bunch of morons. We could have dozens of FH and Glenn flights by 2024. In-orbit assembly is the future of manned space travel. BFR will make SLS look like the joke it is.

I mean, really, with the new changes to the mission lineup, there's no justification for SLS anymore at all. DSG will end up either being super delayed or launched on commercial LVs, and Europa Clipper (assuming it still flies on SLS) will make a slightly faster journey compared to launching on an Atlas or Falcon. What are EM-2 and EM-3 even supposed to do now that they can't co-manifest payloads?

Edited April 23, 2018 by _Augustus_

[Canopus]

38 minutes ago, tater said:

Anything actually variable? Right now SLS can do basically nothing useful as I see it. It can send a capsule into a distant lunar orbit, or it can send a space probe someplace. Other vehicles can also do the same. If a LV is going to literally cost a few billion $ every time it flies, and it is desperate for payloads to justify its existence (vs busywork that merely uses its existence), then it should have as broad a range of applications as possible. That is simply not true right now.

We can change the requirement we use from "mass to LEO" to, "mass to LLO," or mass to TLI, if that gives it a fairer comparison, I suppose.

Here's a question back regarding missions:

What missions do you suggest to be launched once per year to justify the existence of the SLS program? (forgetting that it's just a jobs program that happens to make a rocket)

I was strictly asking why he thinks the ICPS needs more thrust, when all it was ever supposed to launch the 20 something tons of an Orion to TLI or a smaller probe directly to Jupiter, not about the viability of SLS. 

Still currently there is no Launcher with the capabilities of even Block 1 SLS, and it seems they don't want to be dependent on commercial rockets that aren't guaranteed to fly precisely because there is not going to be a constant demand for big missions like this.

Question back to you. What missions in space do you not consider make work? Because in the end of the day thats what all exploratory missions are. Apollo, ISS and all probes existed to create jobs back on earth or show off to someone. Doesn't mean that they didn't return some invaluable information.

27 minutes ago, _Augustus_ said:

http://www.foxnews.com/opinion/2018/04/22/newt-gingrich-glimpse-america-s-future-in-space-in-2024.html

Newt Gingrich: Kill SLS already, otherwise the US looks like a bunch of morons. We could have dozens of FH and Glenn flights by 2024. In-orbit assembly is the future of manned space travel. BFR will make SLS look like the joke it is.

It would look pretty stupid if they cancel the SLS only to see stuff like the BFR greatly reduced in scope because someone realizes that it would never work out the way they thought. Maybe wait until actual replacements are flying regularly and have proven themselves.

Edited April 23, 2018 by Canopus

[tater]

50 minutes ago, Canopus said:

I was strictly asking why he thinks the ICPS needs more thrust, when all it was ever supposed to launch the 20 something tons of an Orion to TLI or a smaller probe directly to Jupiter, not about the viability of SLS. 

The use of ICPS was indeed because it just needed to fly the 25 tons of Orion CSM on a weak-sauce Apollo 8 mission. Now it will likely be the only upper stage for a while, enabling what, exactly? Orion CSM + what cargo?

 

50 minutes ago, Canopus said:

Still currently there is no Launcher with the capabilities of even Block 1 SLS, and it seems they don't want to be dependent on commercial rockets that aren't guaranteed to fly precisely because there is not going to be a constant demand for big missions like this.

When SLS started there were no alternatives on the horizon. The alternatives are literally on the same timeline as SLS at this point (certainly Block 2).

There are no missions for SLS except those which arbitrarily set the requirements ahead of the vehicle even being designed such that only SLS can do it, where "doing it" requires a single launch as an arbitrary given.

 

50 minutes ago, Canopus said:

Question back to you. What missions in space do you not consider make work? Because in the end of the day thats what all exploratory missions are. Apollo, ISS and all probes existed to create jobs back on earth or show off to someone. Doesn't mean that they didn't return some invaluable information.

I actually agree that human space flight is mostly PR/make work.

I none the less think it's possible to set real goals for humans in space. As far as I can tell DSG is just another ISS, but in a worse environment for the astronauts that can only be used infrequently because of uselessly low launch cadence. It's too far from the Moon to provide much inspiring PR, so it fails in the "stunt" category. If we need to work out ECLSS issues, and other human spaceflight stuff via a new station, we should put one in equatorial LEO to minimize rad exposure, and work the issue. Maybe spin a it. The platform is then primarily for testing life support capability, then also spin at variant effective g levels for real data on Moon vs Mars.

If the goal is the Moon (presumably it must be because of DSG), then the vehicle should be able to get crews to the Moon some time before I'm dead of old age.

 

50 minutes ago, Canopus said:

It would look pretty stupid if they cancel the SLS only to see stuff like the BFR greatly reduced in scope because someone realizes that it would never work out the way they thought. Maybe wait until actual replacements are flying regularly and have proven themselves.

The hate for SLS that many of us have stems from the opportunity cost of the program, even as we realize it could never have been any other way.

I understand that minus SLS, that money never goes to NASA, never gets spent on something better... still, given what they did spend, even within the same cost-plus model, SLS could have been far better than it is (the "Direct" architecture mentioned above, for example).

[tater]

Thought experiment:

Go back in time to the start of Constellation/SLS (whenever the common elements start to exist) and ask this question: If Congress guarantees NASA 15 years, and 40-50 billion dollars, what could you design as a crewed follow-on to the Shuttle, with BLEO as the goal using the existing Shuttle contractors and facilities?

I'm pretty sure we could have gotten something better.

If it was also specified that the program could only ever fly 1 mission a year, how would that change things?

 

[NSEP]

I get why people think the SLS is behind, and isn't really significant compared to what other people are planning to do in the future, but keep in mind that SLS and Orion are the closest thing to a manned BLEO spacecraft and launch vehicle we have right now. If say, they cancel the SLS/Orion program right now, NASA, and maybe even the human species, would be taking a step backwards rather than forwards.

You never know, BFR could fail hard, and Orion would be our last hope.

[_Augustus_]

1 hour ago, Canopus said:

It would look pretty stupid if they cancel the SLS only to see stuff like the BFR greatly reduced in scope because someone realizes that it would never work out the way they thought. Maybe wait until actual replacements are flying regularly and have proven themselves.

SLS Block I has a replacement - it's called Falcon Heavy and has already flown. SLS Block I's only advantage over FH is in being able to lob Orion to TLI, and New Glenn should be able to perform that function, as can a dual Vulcan/ACES launch.

Block IB isn't going to fly until 2026 at this rate, and Block II probably never will. Without the EUS, SLS barely even qualifies as an SHLV anymore, and has no practical purpose that a commercial HLV can't fill.

[Canopus]

3 minutes ago, _Augustus_ said:

SLS Block I has a replacement - it's called Falcon Heavy and has already flown. SLS Block I's only advantage over FH is in being able to lob Orion to TLI, and New Glenn should be able to perform that function, as can a dual Vulcan/ACES launch.

So it's only advantage over FH is being actually able to complete the mission it was designed for? Falcon Heavy can't lift Orion to a translunar trajectory so it's not a good replacement. Can't say to much about new glenn, but ACES will only be available in 2024 or 25.

Edited April 23, 2018 by Canopus